JP2020187256A - Fixing device and image forming apparatus - Google Patents

Abstract

To reduce the size of a fixing device using a fixing belt compared with before.SOLUTION: A fixing device 10A comprises: an endless fixing belt 31; a pad part 32 and a driven roller 35 that are arranged opposite to an inner peripheral surface of the fixing belt 31 to stretch the fixing belt 31; a pair of first support parts SP1L, SP1R that are located to sandwich the fixing belt 31 in the width direction of the fixing belt 31, and upon fixation of the pad part 32, support the pad part 32; and a pair of second support parts SP2L, SP2R that are located to sandwich the pair of first support parts SP1L, SP1R in the width direction of the fixing belt 31, and rotatably and pivotally support the driven roller 35.SELECTED DRAWING: Figure 3

Description

The present invention relates to a fixing device for fixing a toner image formed on a recording material such as paper to the recording material, and forms an image by using an electrophotographic method regardless of the type such as color / monochrome. The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile having the fixing apparatus provided in the image forming portion.

Generally, as a fixing device provided in an electrophotographic image forming apparatus, the toner image is fixed to the recording material by applying heat and pressure to the recording material on which the toner image is formed from the viewpoint of safety and efficiency. A heat-fixing method is used. In the heat fixing type fixing device, the recording material on which the toner image is formed is sandwiched between the heating rotating body and the pressurized rotating body to perform fixing.

Various types of heating rotating bodies are known, and one of them is known to use an endless fixing belt from the viewpoint of energy saving. In addition to the fixing belt, the heating rotating body using this fixing belt heats the pad portion where the fixing belt is pressed by the pressurized rotating body, the driven roller that stretches the fixing belt between the pad portion, and the fixing belt. It is generally configured as a fixing belt unit in which heating sources and the like are assembled to each other.

Examples of the fixing device provided with the heating rotating body having the above-described configuration and the image forming device provided with the heating rotating body are disclosed in Japanese Patent Application Laid-Open No. 2008-46663 (Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-46663

Here, in a fixing device provided with a heating rotating body having this type of configuration, it is necessary to support the pad portion and the driven roller by support members such as a chassis at positions on both ends in the width direction of the fixing belt. In particular, since the support portion that supports the driven roller needs to rotatably support the driven roller, it is inevitable that the size of the support portion will increase.

Therefore, in order to configure the fixing device and the image forming device equipped with the fixing device in a compact size, it is necessary to devise some layout so that the pad portion and the support portion supporting the driven roller do not interfere with each other. Become.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to reduce the size of a fixing device using a fixing belt and an image forming device provided with the fixing belt as compared with the conventional ones. ..

The fixing device based on the present invention fixes the toner image formed on the recording material to the recording material, and includes a fixing belt, a heating source, a pad portion, a pressurized rotating body, a driven roller, and the like. It includes a pair of first support portions and a pair of second support portions. The fixing belt has an endless shape, and the heating source heats the fixing belt. The pad portion is arranged so as to face the inner peripheral surface of the fixing belt, and the pressurized rotating body is arranged so as to face the outer peripheral surface of the fixing belt. The pressurized rotating body is rotationally driven in a state where the fixing belt is pressed toward the pad portion to drive the fixing belt, and the recording material is placed between the fixing belt and the outer peripheral surface of the fixing belt. Form a nip to be transported. The driven roller is arranged so as to face the inner peripheral surface of the fixing belt so that the fixing belt is stretched between the pad portion and the driven roller, and the driven roller rotates with the rotation of the fixing belt. .. The pair of first support portions are positioned so as to sandwich the fixing belt in the width direction of the fixing belt, and the pad portions are fixed to support the pad portions. The pair of second support portions are positioned so as to sandwich the pair of first support portions in the width direction of the fixing belt, and rotatably support the driven rollers.

In the fixing device based on the present invention, each of the pair of second support portions may include a bearing, in which case, when viewed along the width direction of the fixing belt, It is preferable that at least a part of the bearing overlaps with at least a part of the pad portion.

In the fixing device based on the present invention, the pad body having the facing surface of the pad portion facing the inner peripheral surface of the fixing belt and the side on which the facing surface is located as viewed from the pad portion are It may include a reinforcing member which is arranged on the opposite side and reinforces the pad body by supporting the pad portion. In that case, when viewed along the width direction of the fixing belt, the above It is preferable that a part of the bearing overlaps at least a part of the reinforcing member.

In the fixing device based on the present invention, the reinforcing member has a flat plate-shaped base facing the pad body and a side where the pad body is located from the base at a position on the upstream side in the transport direction of the recording material. The flat plate-shaped upstream side bearing wall erected toward the opposite side and the downstream side in the transport direction of the recording material are erected from the base toward the side opposite to the side where the pad body is located. It may have a substantially C-shaped cross section including the flat plate-shaped downstream standing wall portion, and in that case, at least the bearing when viewed along the width direction of the fixing belt. It is preferable that a part overlaps at least a part of at least one of the upstream side bearing portion and the downstream side standing wall portion.

In the fixing device based on the present invention, the reinforcing member has a flat plate-shaped base facing the pad body and a side where the pad body is located from the base at a position downstream in the transport direction of the recording material. It may have a substantially L-shaped cross section including a flat plate-shaped downstream standing wall portion erected toward the opposite side, and in that case, along the width direction of the fixing belt. When viewed, it is preferable that at least a part of the bearing overlaps at least a part of the downstream side wall portion.

The fixing device based on the present invention has a first plate-shaped chassis having a bent shape provided on one side of the fixing belt in the width direction and a bent shape provided on the other side of the fixing belt in the width direction. It may be provided with a second plate-shaped chassis having the above. In that case, the first plate-shaped chassis may have a pair of first wall portions facing each other in the width direction of the fixing belt, and the second plate-shaped chassis may have the fixing belt. It may have a pair of second wall portions facing each other in the width direction. Further, in that case, of the pair of first support portions, the first support portion located on the one side in the width direction of the fixing belt is provided on one of the pair of first wall portions. A second support portion located on one side of the pair of second support portions in the width direction of the fixing belt is provided on the other side of the pair of first wall portions. Of the pair of first support portions, the first support portion located on the other side in the width direction of the fixing belt is provided on one of the pair of second wall portions. A second support portion located on the other side of the pair of second support portions in the width direction of the fixing belt is provided on the other side of the pair of second wall portions. It is preferable to have.

The image forming apparatus based on the present invention is provided with the fixing apparatus based on the present invention for image forming.

According to the present invention, it is possible to reduce the size of a fixing device using a fixing belt and an image forming device provided with the fixing belt as compared with the conventional case.

It is the schematic of the image forming apparatus which concerns on Embodiment 1. FIG. It is a schematic cross-sectional view of the fixing device which concerns on Embodiment 1. FIG. It is a schematic plan view of the fixing device shown in FIG. It is the schematic perspective view of the main part of the fixing device shown in FIG. It is a schematic side view of the fixing device which concerns on 1st configuration example. It is a schematic side view of the fixing device which concerns on the 2nd configuration example. It is a schematic side view of the fixing device which concerns on 3rd structural example. It is a schematic side view of the fixing device which concerns on Embodiment 2. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments shown below, as the image forming apparatus and the fixing apparatus to which the present invention is applied, a so-called tandem type color printer adopting an electrophotographic method and a fixing apparatus provided therein will be illustrated and described. .. In the embodiments shown below, the same or common parts are designated by the same reference numerals in the drawings, and the description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic view of an image forming apparatus according to the first embodiment. First, with reference to FIG. 1, a schematic configuration and operation of the image forming apparatus 1 according to the present embodiment will be described.

As shown in FIG. 1, the image forming apparatus 1 mainly includes an apparatus main body 2 and a paper feeding unit 8. The apparatus main body 2 includes an image forming unit 2A which is a portion for forming an image on the paper S as a recording material, and a feeding unit 2B which is a portion for supplying the paper S to the image forming unit 2A. There is. The paper feed unit 8 stores the paper S for supplying to the image forming unit 2A, and is detachably provided in the paper feed unit 2B.

A plurality of rollers 3 are installed inside the image forming apparatus 1, so that the conveying path 4 in which the paper S is conveyed along a predetermined direction is provided in the image forming section 2A and the feeding section 2B described above. It is built across. Further, as shown in FIG. 1, the apparatus main body 2 may be separately provided with a manual feed tray 9 for supplying the paper S to the image forming unit 2A.

The image forming unit 2A includes, for example, an image forming unit 5 capable of forming toner images of each color of yellow (Y), magenta (M), cyan (C), and black (K), and a photosensitive unit 5 included in the image forming unit 5. An exposure unit 6 for exposing the body, an intermediate transfer belt 7a stretched on the image forming unit 5, and a transfer unit 7 provided on the transport path 4 and on the runway of the intermediate transfer belt 7a. It mainly includes a fixing device 10A according to the present embodiment, which will be described later, provided on a transport path 4 in a portion downstream of the transfer unit 7.

The image forming unit 5 receives the exposure from the exposure unit 6 and produces a toner image of each color of yellow (Y), magenta (M), cyan (C) and black (K) or a toner image consisting of only black (K). It is formed on the surface of the photoconductor and transferred to the intermediate transfer belt 7a (so-called primary transfer). As a result, a color toner image or a monochrome toner image is formed on the intermediate transfer belt 7a.

The intermediate transfer belt 7a transfers the color toner image or monochrome toner image formed on the surface thereof to the transfer unit 7, and press-contacts the color toner image or monochrome toner image formed on the surface of the intermediate transfer belt 7a together with the paper S conveyed from the paper feed unit 2B to the transfer unit 7 at the transfer unit 7. Will be done. As a result, the color toner image or monochrome toner image formed on the surface of the intermediate transfer belt 7a is transferred to the paper S (so-called secondary transfer).

The paper S on which the color toner image or the monochrome toner image is transferred is then pressurized and heated by the fixing device 10A. As a result, a color image or a monochrome image is formed on the paper S, and the paper S on which the color image or the monochrome image is formed is then discharged from the apparatus main body 2.

FIG. 2 is a schematic cross-sectional view of the fixing device according to the present embodiment, and FIG. 3 is a schematic plan view of the fixing device shown in FIG. Next, the configuration and operation of the fixing device 10A according to the present embodiment will be described with reference to FIGS. 2 and 3. Note that FIG. 2 is a view showing a cross section of the fixing belt 31 in the central portion in the width direction (that is, a cross-sectional view taken along the line II-II shown in FIG. 3), which is easy to understand in FIG. Therefore, the fixing belt 31 is shown by an imaginary line.

As shown in FIGS. 2 and 3, the fixing device 10A guides the transfer of the pressure roller 20 as a pressure rotating body, the fixing belt unit 30 as a heating rotating body including the fixing belt 31, and the paper S. Various guides 41 to 43 for the purpose are mainly provided.

The pressure roller 20 comprises a metal core metal 21 made of, for example, an aluminum alloy or iron, and a rubber elastic layer 22 made of, for example, silicone rubber or fluororubber, which is provided so as to cover the core metal 21. Includes. The pressure roller 20 may further have a release layer made of, for example, a fluororesin, which is provided so as to cover the elastic layer 22.

As the core metal 21, various shapes such as a solid cylindrical shape or a hollow cylindrical shape can be used, and the outer diameter thereof is not particularly limited, but is, for example, 20 mm or more and 100 mm or less. The thickness of the elastic layer 22 and the thickness of the release layer are not particularly limited, but the thickness of the elastic layer 22 is, for example, 1 mm or more and 20 mm or less, and the thickness of the release layer is, for example, 5 μm or more and 100 μm or less.

The pressure roller 20 is arranged so as to face the outer peripheral surface of the fixing belt 31, and both ends in the axial direction are rotatably supported by a shaft support (not shown). The pressurizing roller 20 is rotationally driven by a drive source (not shown) such as a motor. The pressure roller 20 is configured to be elastically urged toward the fixing belt unit 30 side by an urging member (not shown).

In addition to the fixing belt 31 described above, the fixing belt unit 30 includes a pad portion 32, a heating roller 35 as a driven roller, a heating source 36, an auxiliary pad 37, and a first plate-shaped chassis 38L as a pair of support members. It mainly has a second plate-shaped chassis 38R. Further, the pad portion 32 has a pad main body 33 and a reinforcing member 34.

The fixing belt 31 is endless and is composed of, for example, a plurality of layers in consideration of heat resistance, strength, surface smoothness, and the like. Specifically, the fixing belt 31 is made of, for example, a base material layer made of a polyimide resin or a stainless alloy or nickel electrocasting, an elastic layer made of rubber such as silicone rubber or fluororubber, and a fluororesin or the like. Includes a release layer. These plurality of layers are located in the order of the base material layer, the elastic layer, and the release layer from the inside to the outside of the fixing belt 31.

The circumferential length of the fixing belt 31 is not particularly limited, but for example, the outer diameter of the fixing belt 31 is 10 mm or more and 100 mm or less. The thickness of the base material layer, the thickness of the elastic layer, and the thickness of the release layer are not particularly limited, but the thickness of the base material layer is, for example, 5 μm or more and 100 μm or less, and the thickness of the elastic layer is, for example, 10 μm or more and 300 μm or less. The thickness of the release layer is, for example, 5 μm or more and 100 μm or less.

The pad body 33 is composed of a long plate-shaped member extending along the width direction of the fixing belt 31 (that is, the axial direction of the pressure roller 20), and is arranged in the space inside the fixing belt 31. Has been done. As a result, the pad body 33 faces the inner peripheral surface of the fixing belt 31 so as to face the pressure roller 20 with the fixing belt 31 sandwiched between them, and has the facing surface 33a facing the fixing belt 31. There is.

The pad body 33 is composed of, for example, a resin member made of a liquid crystal polymer resin, a polyphenylene sulfide resin, a polyimide resin, or the like, or a metal member made of an aluminum alloy, iron, or the like. Further, the pad body 33 may be composed of a composite part of any of the above-mentioned members and a rubber member made of, for example, silicone rubber or fluororubber.

The surface of the pad body 33 may be covered with a sliding contact sheet (not shown). As the sliding contact sheet, for example, a sheet in which the surface of a glass fiber woven fabric as a base material is covered with a coat layer made of a fluororesin can be used. When the sliding contact sheet is provided, the slidability between the fixing belt 31 and the pad portion 32 is improved.

The reinforcing member 34 is composed of a long plate-shaped member extending along the width direction of the fixing belt 31, and is located on the side opposite to the side where the pressure roller 20 is located when viewed from the pad body 33. As such, it is arranged in the space inside the fixing belt 31. The reinforcing member 34 is for supporting the pad body 33 and reinforcing the pad body 33.

The reinforcing member 34 is a flat plate-shaped base 34a facing the pad main body 33 and a pair of flat plate-shaped standing wall portions erected from the base 34a toward the side opposite to the side where the pressure roller 20 is located (the said). The standing wall portion has a substantially C-shaped cross section having an upstream side standing wall portion 34b and a downstream side standing wall portion 34c).

The upstream side standing wall portion 34b, which is one of the pair of standing wall portions, is erected from the base portion 34a at the upstream side position (that is, the lower position in FIG. 2) in the transport direction of the paper S, and is a pair of standing walls. The downstream side standing wall portion 34c, which is the other side of the portion, is erected from the base portion 34a at a position on the downstream side in the transport direction of the paper S (that is, a position on the upper side in FIG. 2).

The reinforcing member 34 is made of a metal member such as an electrogalvanized steel sheet (SECC). The reinforcing member 34 is fixed by being supported by a pair of support members including the first plate-shaped chassis 38L and the second plate-shaped chassis 38R at both ends in the width direction. A more specific assembly structure of the reinforcing member 34 (pad portion 32) with respect to the support member will be described in detail later.

In the pad body 33, a positioning pin 33b erected from a main surface located on the opposite side of the pad body 33 from the facing surface 33a is inserted into a through hole provided in the base 34a of the reinforcing member 34. As a result, the hook-shaped locking portion (not shown) provided around the pad body 33 is locked to the peripheral edge of the base portion 34a of the reinforcing member 34, so that the reinforcing member 34 makes it lighter. It is assembled in a held state.

The heating roller 35 is composed of a cylindrical member extending along the width direction of the fixing belt 31 so as to be located on the side opposite to the side where the pressure roller 20 is located when viewed from the pad portion 32. It is arranged in the space inside the fixing belt 31. As a result, the outer peripheral surface of the heating roller 35 faces the inner peripheral surface of the fixing belt 31. The heating roller 35 transfers the heat generated by the heating source 36 to the fixing belt 31.

The heating roller 35 is made of a metal hollow cylindrical member made of, for example, an aluminum alloy. The outer diameter of the heating roller 35 is not particularly limited, but is, for example, 10 mm or more and 100 mm or less. The inner peripheral surface of the heating roller 35 is preferably covered with a black layer in order to efficiently transfer heat, and the outer peripheral surface thereof is covered with a protective layer made of a fluororesin or the like. You may be.

The heating roller 35 has a pair of supports composed of the first plate-shaped chassis 38L and the second plate-shaped chassis 38R by supporting both ends in the width direction by the first plate-shaped chassis 38L and the second plate-shaped chassis 38R. It is rotatably supported by a member. A more specific assembly structure for the support member of the heating roller 35 will be described in detail later.

The heating source 36 includes a pair of rod-shaped heaters, a long heater and a short heater, extending along a direction parallel to the width direction of the fixing belt 31, and is arranged in a space inside the heating roller 35. The heating source 36 heats the fixing belt 31 via a heating roller 35, and both ends in the axial direction thereof are held by holding portions (not shown). Both the long heater and the short heater consist of halogen heaters, for example.

The long heater has a heat generating portion in a region corresponding to substantially the entire width direction of the fixing belt 31, and when the heat generating portion generates heat, the fixing belt 31 is heated mainly by the radiant heat thereof via the heating roller 35. Is what you do. The axial length of the heat generating portion corresponds to the width of the paper having the maximum width among the various sizes of paper supplied to the image forming apparatus 1.

The short heater has a heat generating portion only in a region corresponding to the central portion in the width direction of the fixing belt 31, and when the heat generating portion generates heat, the fixing belt 31 is moved mainly by the radiant heat via the heating roller 35. It is to be heated. The axial length of the heat generating portion corresponds to the width of the paper having the smallest width among the various sizes of paper supplied to the image forming apparatus 1.

As the heating source 36, an IH (electromagnetic induction heating) type heating source or the like can be used in addition to the halogen heater described above, and further, a heating roller 35 or a fixing belt 31 may be used. By forming a resistance heating element, these can also be used as a heating source.

The auxiliary pad 37 is composed of a long plate-shaped member extending along the width direction of the fixing belt 31, and is provided on the reinforcing member 34 so as to be arranged in the space inside the fixing belt 31. It is fixed on the outer surface of the downstream side standing wall portion 34c. The auxiliary pad 37 is a guide for guiding the fixing belt 31, and also applies a lubricant to the inner peripheral surface of the fixing belt 31.

More specifically, the auxiliary pad 37 is provided at a position downstream of the nip portion N, which will be described later, in the rotation direction of the fixing belt 31, and has a lubricant supply portion 37a as a coating portion. The lubricant supply unit 37a is made of felt impregnated with a lubricant such as grease, and when the inner peripheral surface of the fixing belt 31 comes into contact with the lubricant supply unit 37a, the lubricant is applied to the fixing belt. It is supplied to the inner peripheral surface of 31. As a result, the slidability between the fixing belt 31 and the pad portion 32 is improved.

Here, as described above, the pressure roller 20 is configured to be elastically urged toward the fixing belt unit 30 side by an urging member (not shown). Therefore, the pressure roller 20 is elastically urged in the direction approaching the fixing belt 31 by the urging force of the urging member, so that the fixing belt 31 is pressed toward the pad portion 32 by the pressure roller 20. .. As a result, the pressed state in which the pad portion 32 is pressed by the pressurizing roller 20 is realized.

On the other hand, the fixing belt 31 is stretched on the pad portion 32, the heating roller 35, and the auxiliary pad 37 described above. As a result, the fixing belt 31 can rotate so as to slide on the main surface of the pad portion 32 on the pressure roller 20 side (that is, on the facing surface 33a of the pad body 33 described above), and this rotation causes the fixing belt 31 to slide. The portion of the fixing belt 31 in contact with the heating roller 35 is heated by the heating source 36, and then the portion of the fixing belt 31 moves to the nip portion N, which will be described later, to supply the paper to the nip portion N. The toner image formed on the S and the paper S is heated by the portion of the fixing belt 31.

That is, in the fixing device 10A according to the present embodiment, as described above, in a state where the pressure roller 20 is urged toward the fixing belt unit 30, the pressure roller 20 does not show the above-mentioned drive source (not shown). By being rotationally driven in the direction of arrow A shown in FIG. 2, the fixing belt 31 is driven to rotate in the direction of arrow B shown in FIG. 2 so as to slide on the pad portion 32. At this time, the heating roller 35 as the driven roller also rotates in a driven manner.

As a result, a nip portion N through which the paper S is conveyed is formed between the pressurizing roller 20 and the pad portion 32 (more strictly, between the pressurizing roller 20 and the outer peripheral surface of the fixing belt 31). Will be. In other words, the pressure roller 20 and the fixing belt unit 30 are arranged so as to sandwich the transport path 4 so that the nip portion N formed between them is located on the paper transport path 4. Has been done.

An inlet side guide 41 is provided at a position on the transport path 4 on the upstream side of the nip portion N (that is, a position on the lower side in FIG. 2) along the transport direction of the paper S. There is. The inlet side guide 41 is a guide for ensuring that the paper S sent on the transport path 4 is loaded into the nip portion N.

Further, at a position on the transport path 4 on the downstream side of the nip portion N along the transport direction of the paper S (that is, a position on the upper side in FIG. 2), the separation guide 42 and the outlet A side guide 43 is provided. The separation guide 42 is a guide for separating the paper S, which is in close contact with the fixing belt 31 when discharged from the nip portion N, from the fixing belt 31, and the outlet side guide 43 is provided by the separation guide 42. This is a guide for surely returning the paper S separated from the fixing belt 31 onto the transport path 4.

By having the above configuration, in the fixing device 10A according to the present embodiment, heat and heat are generated with respect to the toner image formed on the paper S during the fixing operation (that is, in the pressing state described above). Pressure will be applied at the nip portion N, whereby the toner image will be fixed on the paper S.

FIG. 4 is a schematic perspective view of a main part of the fixing device shown in FIG. Here, FIG. 4 shows the structure of the end portion of the fixing belt unit 30 on the side where the above-mentioned first plate-shaped chassis 38L is located. In FIG. 4, the fixing belt 31 is not shown. ing. Next, with reference to FIGS. 3 and 4 described above, the pad portion 32 and the heating roller 35 in the fixing device 10A according to the present embodiment are assembled to the first plate-shaped chassis 38L and the second plate-shaped chassis 38R. The structure will be explained in detail.

As shown in FIG. 3, the first plate-shaped chassis 38L is composed of a metal member having a bent shape arranged on one side (that is, the left side in FIG. 3) in the width direction of the fixing belt 31. The fixing belt 31 has a pair of first wall portions 381L and 382L located opposite to each other along the width direction of the fixing belt 31. The first wall portions 381L and 382L are arranged in this order from the central portion to the outside of the fixing device 10A. That is, the first wall portion 381L is arranged closer to the fixing belt 31 than the first wall portion 382L.

The second plate-shaped chassis 38R is made of a metal member having a bent shape arranged on the other side in the width direction of the fixing belt 31 (that is, the right side in FIG. 3), and the width of the fixing belt 31 is wide. It has a pair of second wall portions 381R and 382R located opposite to each other along the direction. The second wall portions 381R and 382R are arranged in this order from the central portion to the outside of the fixing device 10A. That is, the second wall portion 381R is arranged closer to the fixing belt 31 than the second wall portion 382R.

As shown in FIG. 3 and particularly in FIG. 4, the first plate-shaped chassis 38L is located on one side (that is, the left side in FIG. 3) of the pad portion 32 in the width direction of the fixing belt 31. One of the first support portion SP1L that fixedly supports the end portion (hereinafter, the end portion is referred to as "the left end portion of the pad portion 32" for convenience) and the fixing belt 31 of the heating rollers 35 in the width direction. With the second support portion SP2L that rotatably supports the end portion (hereinafter, the end portion is referred to as "the left end portion of the heating roller 35" for convenience) located on the side (that is, the left side in FIG. 3). Is provided.

Specifically, as shown in FIG. 4, the first wall portion 381L of the first plate-shaped chassis 38L is provided with a hole having a substantially rectangular shape in a plan view, and the end portion of the reinforcing member 34 is the hole. By being fitted into the portion, the left end portion of the pad portion 32 is fixed by being assembled to the first plate-shaped chassis 38L. That is, the portion of the first wall portion 381L of the first plate-shaped chassis 38L provided with the hole portion functions as the first support portion SP1L.

Further, the first wall portion 382L of the first plate-shaped chassis 38L is provided with a hole having a substantially circular shape in a plan view, and the left end portion of the heating roller 35 is inserted into the hole. Here, a bearing 383L is previously assembled in the hole provided in the first wall portion 382L, and a substantially cylindrical bush 384L is previously assembled in the left end portion of the heating roller 35. There is. Therefore, the bush 384L assembled to the heating roller 35 is press-fitted into the bearing 383L assembled to the first wall portion 382L, so that the left end portion of the heating roller 35 is inserted into the hole portion. Become.

As a result, the left end portion of the heating roller 35 is rotatably supported by the first plate-shaped chassis 38L via the bearing 383L and the bush 384L. That is, the portion of the first wall portion 382L of the first plate-shaped chassis 38L provided with the hole portion, the bush 384L and the bearing 383L function as the second support portion SP2L.

On the other hand, although detailed illustration thereof is omitted here, as shown in FIG. 3, the second wall portion 381R of the second plate-shaped chassis 38R is provided with a hole having a substantially rectangular shape in a plan view and is reinforced. The end portion of the member 34 is fitted into the hole portion, so that the right end portion of the pad portion 32 is assembled to the second plate-shaped chassis 38R and fixed. That is, the portion of the second wall portion 381R of the second plate-shaped chassis 38R provided with the hole portion functions as the first support portion SP1R.

Further, the second wall portion 382R of the second plate-shaped chassis 38R is provided with a hole having a substantially circular shape in a plan view, and the right end portion of the heating roller 35 is inserted into the hole. Here, a bearing 383R is previously assembled in the hole provided in the second wall portion 382R, and a substantially cylindrical bush 384R is previously assembled in the right end of the heating roller 35. There is. Therefore, the bush 384R assembled to the heating roller 35 is press-fitted into the bearing 383R assembled to the second wall portion 382R, so that the right end portion of the heating roller 35 is inserted into the hole portion. Become.

As a result, the right end portion of the heating roller 35 is rotatably supported by the second plate-shaped chassis 38R via the bearing 383R and the bush 384R. That is, the portion of the second wall portion 382R of the second plate-shaped chassis 38R provided with the hole portion, the bush 384R and the bearing 383R function as the second support portion SP2R.

As described above, the pair of first support portions SP1L and SP1R are provided on the first plate-shaped chassis 38L and the second plate-shaped chassis 38R so as to sandwich the fixing belt 31 in the width direction of the fixing belt 31, and the pads are provided. The portion 32 is supported by the pair of first support portions SP1L and SP1R.

Further, a pair of second support portions SP2L and SP2R are provided on the first plate-shaped chassis 38L and the second plate-shaped chassis 38R so as to sandwich the pair of first support portions SP1L and SP1R in the width direction of the fixing belt 31. Therefore, the heating roller 35 is rotatably supported by the pair of second support portions SP2L and SP2R.

That is, by adopting the above configuration, the pair of first support portions SP1L and SP1R that support the pad portion 32 and the second support portions SP2L and SP2R that rotatably support the heating roller 35 are formed by the fixing belt 31. Since the pads 32 and the portions supporting the heating roller 35 are supported at different positions in the width direction of the above, the pad portion 32 and the heating roller 35 are brought close to each other while avoiding interference with each other. Can be placed.

Therefore, by adopting the configuration as in the present embodiment, the pad portion 32 and the driven roller can be arranged closer to each other, so that the fixing device is smaller than the conventional one. It can be 10A and the image forming apparatus 1 provided with this. Furthermore, by adopting the above configuration, the length of the fixing belt 31 itself in the circumferential direction can be shortened, so that the heat capacity of the fixing belt 31 can be reduced, and energy saving can be achieved as compared with the conventional case. be able to.

5 to 7 are schematic side views of the fixing device according to the first to third configuration examples. As in the present embodiment, the pair of first support portions SP1L and SP1R that support the pad portion 32 and the pair of second support portions SP2L and SP2R that pivotally support the heating roller 35 are placed at different positions in the width direction of the fixing belt 31. As a specific layout when the pad portion 32 and the heating roller 35 are arranged close to each other while being provided, three layouts of the first to third configuration examples shown in FIGS. 5 to 7 are assumed. To. Hereinafter, each layout will be described.

Here, the first configuration example shown in FIG. 5 shows the layout of the fixing device 10A itself according to the present embodiment shown in FIGS. 2 to 4, and the side view shown in FIG. 5 is shown in FIG. It is a side view when viewed from the arrow V direction shown. Further, the second and third configuration examples shown in FIGS. 6 and 7 are obtained by appropriately changing the installation position of the heating roller 35 in the first configuration example, respectively, and the side views shown in FIGS. 6 and 7 are shown in FIGS. It is a side view when viewed from the same direction as the side view shown in 5. In FIGS. 5 to 7, the first plate-shaped chassis 38L is not shown for ease of understanding.

As shown in FIG. 5, in the fixing device 10A according to the first configuration example, a part of the bearing 383L assembled to the left end portion of the heating roller 35 when viewed along the width direction of the fixing belt 31. Is heated so as to overlap the rear end portion of the upstream side standing wall portion 34b provided on the reinforcing member 34 of the pad portion 32 (that is, the end portion of the upstream side standing wall portion 34b located on the side opposite to the base portion 34a side). The roller 35 is arranged close to the pad portion 32 (see region R1 shown in FIG. 5). In this case, although not shown in FIG. 5, a part of the bearing 383R assembled to the right end of the heating roller 35 is also reinforced by the pad portion 32 when viewed along the width direction of the fixing belt 31. It overlaps with the rear end portion of the upstream side bearing wall portion 34b provided on the member 34.

With this configuration, the distance D between the rotation axis of the heating roller 35 to which these bearings 383L and 383R are assembled and the rotation axis of the pressure roller 20 is approximately orthogonal to the transport direction of the paper S. It can be shortened in the direction. Therefore, the outer diameter of the fixing device 10A in the relevant direction can be reduced, and the circumferential length of the fixing belt 31 can be shortened by that amount.

As shown in FIG. 6, in the fixing device 10A1 according to the second configuration example, a part of the bearing 383L assembled to the left end portion of the heating roller 35 when viewed along the width direction of the fixing belt 31. Is heated so as to overlap the rear end portion of the downstream side standing wall portion 34c provided on the reinforcing member 34 of the pad portion 32 (that is, the end portion of the downstream side standing wall portion 34c located on the side opposite to the base portion 34a side). The roller 35 is arranged close to the pad portion 32 (see region R2 shown in FIG. 6). In this case, although not shown in FIG. 6, a part of the bearing 383R assembled to the right end portion of the heating roller 35 is also reinforced by the pad portion 32 when viewed along the width direction of the fixing belt 31. It overlaps with the rear end portion of the downstream side bearing wall portion 34c provided on the member 34.

With this configuration, the distance D between the rotation axis of the heating roller 35 to which these bearings 383L and 383R are assembled and the rotation axis of the pressure roller 20 is approximately orthogonal to the transport direction of the paper S. It can be shortened in the direction. Therefore, the outer diameter of the fixing device 10A1 in the relevant direction can be reduced, and the circumferential length of the fixing belt 31 can be shortened by that amount.

As shown in FIG. 7, in the fixing device 10A2 according to the third configuration example, a part of the bearing 383L assembled to the left end portion of the heating roller 35 when viewed along the width direction of the fixing belt 31. However, the heating roller 35 is arranged close to the pad portion 32 so as to overlap the rear end portion of the upstream side standing wall portion 34b and the rear end portion of the downstream side standing wall portion 34c provided on the reinforcing member 34 of the pad portion 32. (See regions R1 and R2 shown in FIG. 7). In this case, although not shown in FIG. 7, a part of the bearing 383R assembled to the right end of the heating roller 35 is also reinforced by the pad portion 32 when viewed along the width direction of the fixing belt 31. It overlaps the rear end portion of the upstream side bearing wall portion 34b and the rear end portion of the downstream side bearing wall portion 34c provided on the member 34.

With this configuration, the distance D between the rotation axis of the heating roller 35 to which these bearings 383L and 383R are assembled and the rotation axis of the pressure roller 20 is approximately orthogonal to the transport direction of the paper S. It can be shortened in the direction. Therefore, the outer diameter of the fixing device 10A2 in the relevant direction can be reduced, and the circumferential length of the fixing belt 31 can be shortened by that amount.

(Embodiment 2)
FIG. 8 is a schematic side view of the fixing device according to the second embodiment. Hereinafter, the fixing device 10B according to the present embodiment will be described with reference to FIG. In FIG. 8, the first plate-shaped chassis 38L is not shown for ease of understanding.

The fixing device 10B according to the present embodiment is provided in the image forming device 1 in place of the fixing device 10A according to the above-described first embodiment. As shown in FIG. 8, the fixing device 10B according to the present embodiment has a different configuration of the reinforcing member 34 in the pad portion 32 when compared with the fixing device 10A according to the above-described first embodiment. is there.

Specifically, the reinforcing member 34 of the fixing device 10B according to the present embodiment is erected from the flat plate-shaped base 34a facing the pad main body 33 and the base 34a at a position on the downstream side in the transport direction of the paper S. It has a substantially L-shaped cross section with the downstream side standing wall portion 34c, and the upstream side standing wall portion 34b (FIG. 2) of the reinforcing member 34 of the fixing device 10A according to the first embodiment described above. And see Fig. 5 etc.).

Here, even in the fixing device 10B according to the present embodiment, as in the case of the fixing device 10A according to the above-described first embodiment, the pair of first support portions SP1L, SP1R and SP1R supporting the pad portion 32 The pair of second support portions SP2L and SP2R that pivotally support the heating roller 35 are provided at different positions in the width direction of the fixing belt 31 (see FIGS. 3 and 4 and the like).

Further, in the fixing device 10B according to the present embodiment, when viewed along the width direction of the fixing belt 31, a part of the bearing 383L assembled to the left end portion of the heating roller 35 is a pad portion 32. The heating roller 35 is arranged close to the pad portion 32 so as to overlap the rear end portion of the downstream side vertical wall portion 34c provided on the reinforcing member 34 of the above (see region R2 shown in FIG. 8). Although not shown in FIG. 8, a part of the bearing 383R assembled to the right end of the heating roller 35 is also a reinforcing member of the pad portion 32 when viewed along the width direction of the fixing belt 31. It overlaps with the rear end portion of the downstream side bearing wall portion 34c provided on the 34.

Even in this configuration, the distance between the rotating shaft of the heating roller 35 to which the bearings 383L and 383R are assembled and the rotating shaft of the pressurizing roller 20 is the same as in the case of the first embodiment described above. D can be shortened in a direction substantially orthogonal to the transport direction of the paper S. Therefore, the outer diameter of the fixing device 10B in the relevant direction can be reduced, and the circumferential length of the fixing belt 31 can be shortened by that amount.

Therefore, even when the configuration as in the present embodiment is adopted, as in the case of the above-described first embodiment, the fixing device 10B is miniaturized and energy-saving as compared with the conventional case. And the image forming apparatus 1 provided with this.

(Other forms, etc.)
In the above-described first and second embodiments, when viewed along the width direction of the fixing belt, a part of the bearing assembled to the heating roller as the driven roller is one of the reinforcing members in the pad portion. Although the case where the bearing is configured to overlap the parts has been described as an example, a part of the bearing is configured to overlap a part of the pad body of the pad part in addition to or in place of the reinforcing member. It may have been done.

Further, the bearing does not necessarily have to overlap the pad portion when viewed along the width direction of the fixing belt. Even in that case, if the pair of first support portions that support the pad portions and the pair of second support portions that pivotally support the heating rollers are provided at different positions in the width direction of the fixing belt, the fixing device is not a little. Will contribute to the miniaturization of.

Further, in the above-described first and second embodiments, one of the pair of first support portions that support the pad portion and one of the pair of second support portions that pivotally support the heating roller as the driven roller are bent. A second having a bent shape is provided on the first plate-shaped chassis having a shape, and the other of the pair of first support portions that support the pad portion and the other of the pair of second support portions that pivotally support the heating roller are bent. Although the description has been made by exemplifying the case where the chassis is provided in the plate-shaped chassis, it is not always necessary to have such a configuration.

For example, one of the pair of first support portions that support the pad portion and one of the pair of second support portions that pivotally support the heating roller are provided in different chassis, and the pair of first support portions that support the pad portion are provided. The other of the support portions and the other of the pair of second support portions that pivotally support the heating roller may be provided in different chassis.

Further, in the above-described first and second embodiments, the case where the present invention is applied to a so-called tandem type color printer adopting an electrophotographic method and a fixing device provided therein has been described as an example. The application target of the present invention is not limited to this, and the present invention can be applied to various image forming devices adopting an electrophotographic method and a fixing device provided therein.

As described above, the above-described embodiment disclosed this time is an example in all respects and is not limiting. The technical scope of the present invention is defined by the scope of claims and includes all modifications within the meaning and scope equivalent to the description of the scope of claims.

1 image forming device, 2 device body, 2A image forming unit, 2B paper feeding unit, 3 rollers, 4 transport paths, 5 image forming unit, 6 exposure unit, 7 transfer unit, 7a intermediate transfer belt, 8 paper feeding unit, 9 Bypass tray, 10A, 10A1, 10A2, 10B Fixing device, 20 Pressurizing roller, 21 Core metal, 22 Elastic layer, 30 Fixing belt unit, 31 Fixing belt, 32 Pad part, 33 Pad body, 33a facing surface, 33b Positioning pin , 34 Reinforcing member, 34a base, 34b upstream side wall, 34c downstream side wall, 35 heating roller, 36 heating source, 37 auxiliary pad, 37a lubricant supply, 38L 1st plate chassis, 38R 2nd plate Chassis, 381L, 382L 1st wall, 381R, 382R 2nd wall, 383L, 383R bearing, 384L, 384R bush, 41 inlet side guide, 42 separation guide, 43 exit side guide, N nip part, S paper, SP1R, SP1L first support part, SP2R, SP2L second support part.

Claims (7)

A fixing device that fixes a toner image formed on a recording material to the recording material.
With an endless fixing belt,
A heating source for heating the fixing belt and
A pad portion arranged so as to face the inner peripheral surface of the fixing belt and
The fixing belt is arranged so as to face the outer peripheral surface of the fixing belt, and is rotationally driven in a state where the fixing belt is pressed toward the pad portion, whereby the fixing belt is driven to rotate and the outer peripheral surface of the fixing belt is driven. A pressurized rotating body that forms a nip to which the recording material is transported between
A driven roller that is arranged so as to face the inner peripheral surface of the fixing belt so that the fixing belt is stretched between the pad portion and is driven to rotate with the rotation of the fixing belt.
A pair of first support portions that are positioned so as to sandwich the fixing belt in the width direction of the fixing belt and that support the pad portion by fixing the pad portion.
A fixing device including a pair of second support portions that are positioned so as to sandwich the pair of first support portions in the width direction of the fixing belt and rotatably support the driven roller. Each of the pair of second supports includes bearings.
The fixing device according to claim 1, wherein at least a part of the bearing overlaps at least a part of the pad portion when viewed along the width direction of the fixing belt. The pad portion is arranged on the side opposite to the pad body having the facing surface facing the inner peripheral surface of the fixing belt and the side on which the facing surface is located when viewed from the pad portion to support the pad portion. This includes a reinforcing member that reinforces the pad body.
The fixing device according to claim 2, wherein at least a part of the bearing overlaps at least a part of the reinforcing member when viewed along the width direction of the fixing belt. The reinforcing member is a flat plate erected from the base portion toward the side opposite to the side where the pad body is located at a position on the upstream side in the transport direction of the recording material and the flat plate-shaped base portion facing the pad body. Includes a flat upstream side standing wall portion and a flat plate-shaped downstream side standing wall portion erected from the base portion toward the side opposite to the side where the pad body is located at a position on the downstream side in the transport direction of the recording material. It has a substantially C-shaped cross section and has a shape.
3. Claim 3 that at least a part of the bearing overlaps at least a part of at least one of the upstream side standing wall portion and the downstream side standing wall portion when viewed along the width direction of the fixing belt. The fixing device according to. The reinforcing member is erected from the base portion toward the side opposite to the side where the pad body is located at a position on the downstream side in the transport direction of the recording material from the flat plate-shaped base portion facing the pad body. It has a substantially L-shaped cross section including the downstream side wall portion.
The fixing device according to claim 3, wherein at least a part of the bearing overlaps at least a part of the downstream side standing wall portion when viewed along the width direction of the fixing belt. A first plate-shaped chassis having a bent shape provided on one side in the width direction of the fixing belt, and
A second plate-shaped chassis having a bent shape provided on the other side in the width direction of the fixing belt is provided.
The first plate-shaped chassis has a pair of first wall portions facing each other in the width direction of the fixing belt.
The second plate-shaped chassis has a pair of second wall portions facing each other in the width direction of the fixing belt.
Of the pair of first support portions, a first support portion located on the one side in the width direction of the fixing belt is provided on one of the pair of first wall portions.
A second support portion located on the one side of the pair of second support portions in the width direction of the fixing belt is provided on the other side of the pair of first wall portions.
Of the pair of first support portions, a first support portion located on the other side in the width direction of the fixing belt is provided on one of the pair of second wall portions.
Claim 1 in which a second support portion located on the other side of the pair of second support portions in the width direction of the fixing belt is provided on the other side of the pair of second wall portions. The fixing device according to any one of 5 to 5. An image forming apparatus comprising the fixing apparatus according to any one of claims 1 to 6 for image forming.

Images